Mike Pompeo
Mike PompeoReuters

US Secretary of State Mike Pompeo on Thursday accused Iran of being behind attacks on two tankers in the Gulf of Oman, saying he was taking the case to the UN Security Council.

"It is the assessment of the United States that the Islamic Republic of Iran is responsible for the attacks," Pompeo told reporters, according to AFP.

"This is based on intelligence, the weapons used, the level of expertise needed to execute the operation, recent similar Iranian attacks on shipping, and the fact that no proxy group operating in the area has the resources and proficiency to act with such a high degree of sophistication," he added.

Pompeo said Iran "promised" on April 22 to disrupt oil shipping from the Strait of Hormuz.

"It is now executing that promise," he said.

He said the attacks Thursday, which left two tankers in flames off Iran's south coast, were part of a series of attacks instigated by Tehran and its surrogates.

"Taken as a whole, these unprovoked attacks present a clear threat to international security, a blatant assault on the freedom of navigation, and an unacceptable campaign of escalating tension by Iran," the top US diplomat said.

Pompeo added that Iran is lashing out because of the impact of US and international sanctions, but said it had no right "to attack innocent civilians and engage in nuclear blackmail."

Pompeo said he had ordered the US envoy to the United Nations, Jonathan Cohen, to raise the alleged attacks in a UN Security Council meeting.

Thursday’s incident follows attacks on four tankers off the coast of the United Arab Emirates on May 12. Two of the ships targeted in that attack were Saudi oil tankers that were en route to the United States.

An American military team assessing the blasts that damaged the four commercial ships blamed Iran or Iranian-backed proxies using explosive charges.

The UAE last week said the May 12 attack bore the hallmarks of a “sophisticated and coordinated operation,” most likely by a state actor, though it did not specifically name Iran.

Pompeo on Thursday said US policy aims to bring Iran back into negotiations over its nuclear program and regional activities.

However, he added, "The United States will defend its forces, interests and stand with our partners and allies to safeguard global commerce and regional stability."

"And we call upon all nations threatened by Iran to join us in that endeavor," he added.

The two attacks followed repeated threats by Iran to close the strategic Strait of Hormuz, which is located at the mouth of the Persian Gulf and through which about a third of all oil traded at sea passes.

In the last few years there have been several close encounters between Iranian and American vessels in the area.

Late last year, a commander in the Iranian Revolutionary Guards threatened US bases in Afghanistan, the UAE and Qatar, as well as US aircraft carriers in the Gulf. These bases, he said, are within range of Iranian missiles which have a range of 700 km (450 miles).